Apparatus for controlling the rotational speed of the spindles of a spinning preparatory machine

ABSTRACT

The invention concerns an apparatus for controlling the rotational speed of the spindles of a spinning preparatory machine equipped with spindles and flyers. 
     The proposed control arrangement comprises an infinitely variable variator, which is adapted or adjusted by using a control shaft which is rotatably indexed or stepped. The control or adjustment shaft is moved by a control motor which received its control or switching impulses from a motor control device comprising a programmable indicator or set value transmitter for the desired or set value and a correction element. 
     According to a particularly advantageous design the correction element is of the form of a crossbar distributor arrangement. 
     The apparatus is comfortable and easy to use by the operating personnel and permits, among other advantages, extremely accurate adaptation or adjustment of the spindle rotational speed. The adaption operations can be effected while the machine is running.

BACKGROUND OF THE INVENTION

The present invention concerns an apparatus for controlling therotational speed of the spindles of a spinning preparatory machineequipped with spindles and with flyers operatively coordinated thereto,as a function of the increasing bobbin diameter. The control apparatuscontains a variator for driving the spindles, and such variator can beinfinitely varied by using a control shaft which is stepwise rotated.

In a spinning preparatory machine of this type, also called roving frameor fly frame, a fibre roving is produced and is wound in parallelwindings onto the bobbin of each spinning position, using a flyer. Asthe fibre roving is to be draftable as input material to be fed to thenext processing step, a very low twist is imparted to it, barelysufficient for tensionless transfer of the fibre roving to a draftingarrangement of the subsequent processing step, but resulting in anundesirable faulty draft in the roving under the smallest tensilestress.

With such spinning preparatory machines it is necessary to drive boththe spindle, and the flyer, which distributes the fibre roving over thebobbin surface and which flyer rotates coaxially with the spindle, andfurthermore to precisely adjust the mutual rotational speeds.

In this arrangement the flyer, as a rule, rotates at a constantrotational speed, while the rotational speed of the spindle is adaptedaccording to the increasing bobbin diameter: the spindle, in thisarrangement, performs the reciprocating spindle rail stroke between tworeversal points moving with respect to space as a function of the bobbindiameter, this traversing stroke ensuring for both the winding of thefibre roving in parallel windings onto the bobbin surface and theconical built or formed shape of the bobbin extremities.

The present invention deals with the problem of adapting the rotationalspeed of the spindle to the increasing bobbin diameter, and there is notspecifically involved the reduction of the spindle rail traverse strokeas a function of the bobbin diameter.

The increase of the bobbin diameter, however, decisively depends on thetechnological properties of the roving produced, such as e.g. fibre typeand quality, count (or linear density), twist, volume, etc. Experiencehas shown, that e.g. the volume of a roving of this type, or itscross-section respectively, depends on the air or climatic conditions,i.e. it can vary over time, and that also such minute variations alreadyconstitute a disturbing factor in the winding process, which is to becorrected using suitable means.

In the state of the art, countless propositions for controlling therotational speed of a spinning preparatory machine of this type areknown, in which machine, for obtaining the precision control which isrequired, usually a coarse control device and a fine control device areapplied working in combination. Using the coarse control device, thebest known form of which and that which is most universally utilized isa double-cone belt drive arrangement, the rotational speed of thespindle is roughly adapted to the geometric dimensions of the bobbin andin particular to its diameter. Using the fine control device, whichfrequently is in the form of a multi-member compensating rail, the speedratio of the cone belt drive is influenced and a fine correction of theroving tension at different diameters of the bobbin is effected.

A solution of this type is shown, e.g. in Swiss Pat. No. 569,806. As acorrecting rail here a control surface is used, which over the wholezone of the belt shifting of the cone belt drive exerts a correctinginfluence thereon. In a solution of this type with a double cone beltdrive arrangement, of course, also adaption of the average speed of thebelt shifting movement to the roving volume is required, which as a ruleis effected by insertion of a gear train with exchangeable gears.Typical for this solution is the application of an infinitely variablevariator, which is adjusted by a control shaft, which is rotatedstepwise. The disadvantages of this known solution reside in its pooroperatability and in its complicated design. Setting the elements forthe rough control (e.g. the change gear for shifting the double conebelt) as well as for the fine control is to be effected while themachine is at a standstill, as manipulations are performed at the geartrain. The whole operation of adjusting the settings of the controlelements, which is to be extended over several complete doff cycles, ifthe success of the adjustments effected is to be judged, is verytime-consuming and complicated, and thus the spinning preparatorymachine in many cases is not set optimally but to approximate accuracyonly. The resulting faulty drafts in the roving and an increased numberof roving breakages result in corresponding stoppages, causing downtimeand deterioration in machine efficiency.

Also the adaption to the variable air conditions in the spinning roomproves very problematic in view of the above mentioned operationaldisadvantages of the known devices.

A further disadvantage of the known device is seen in that it requires agreat deal of maintenance, particularly cleaning and lubricationoperations. Furthermore, in a device of such type the disadvantage is tobe mentioned that the control elements are to be equipped withparticular resetting elements, using e.g. the belt of the double conebelt drive which is to be brought back into its starting position afterthe belt has been released while the machine is at a standstill. Forthis purpose, e.g. a releasing device for the cones and a separateresetting motor, which are active merely during the very short timeperiod of the resetting operation, are required, the device thusbecoming still more complicated and expensive.

Solutions similar to the one described here are described e.g. in FrenchPat. No. 15 66 512 and in German Patent Application No. 12 91 664. Forthese the disadvantages cited in connection with the above mentionedstate of the art also apply.

In other known devices for a spinning preparatory machine, control ofthe rotational speed of the spindle is effected in that the rovingtension is maintained constant, which implies that the roving tension ismeasured.

This control technique, based only on the winding conditions atindividual spinning positions, requires a relatively complexinstallation of measuring instruments, but does not ensure that theroving tension is correct at the other spinning positions. If,unfortunately, just the one spinning position at which the rovingtension is measured, runs extremely tight or extremely slack, all otherspinning positions which might run correctly are correctedcorrespondingly in such a manner that, at these spinning positions, thecomplexity of the arrangement notwithstanding, optimum spinningconditions are not obtained.

SUMMARY OF THE INVENTION

It thus is an object of the present invention to eliminate thedisadvantages heretofore mentioned of the known devices and to proposean apparatus of the above mentioned type, in which in particular:

(a) Setting of the rotational speed of the spindles, or the control ofthe roving tension, respectively, is extremely accurate and simple overthe whole bobbin build or formation;

(b) Setting of the rotational speed of the spindles is possible whilethe machine is running;

(c) Operation of the apparatus is simple, maintenance work required isreduced, and no separate resetting elements are required.

These and other advantages can be achieved by an apparatus forcontrolling the rotational speed of the spindles in a spinningpreparatory machine, equipped with spindles and with flyers coordinatedthereto, as a function of the increasing bobbin diameter, using aninfinitely variable variator adjusted by a control shaft rotatedstepwise, for the drive of the spindles, in that the control shaft isdriven by an electrical setting motor, which receives control impulsesfrom a motor control device, the motor control device comprising aprogrammable indicator of the desired value, and an adjustablecorrection element, using the impulse member set on the desired valueindicator which can be corrected in each control step by adding or bysubtracting correction impulses, and in that the command for generationof control impulses for the motor control is activated by a devicescanning the reversal points of the spindle rail traversing movementand/or that the correcting element is connected with a device scanningthe increasing bobbin diameter. The drive arrangement for the controlshaft for adjusting the variator using a setting motor creates theprerequisite conditions for achieving the above mentioned advantages, asdescribed in more detail in the following with reference to illustrateddesign examples.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and objects other than those setforth above, will become apparent when consideration is given to thefollowing detailed description thereof. Such description makes referenceto the annexed drawings wherein:

FIG. 1 is an overall view of a spinning preparatory machine equippedwith the inventive control apparatus;

FIG. 2 is a block diagram of an inventive control apparatus forcontrolling a spinning preparatory machine as shown in FIG. 1; and

FIG. 3 is a block diagram of an inventive alternative design example ofthe apparatus for controlling a spinning preparatory machine accordingto FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1 a spinning preparatory machine is shown, equipped withspindles and with flyers coordinated thereto, in a schematic andsimplified view, showing the working elements as far as required forunderstanding the invention.

A spinning preparatory machine of such type comprises spindles 2rotatably supported in one row or in a plurality of rows on a spindlerail 1, one spindle 2 only being shown to simplify the illustration. Thespindle rail 1 is traversed up and down vertically, and for this purposeis guided in vertical guides not shown, and is coupled with a traversingmechanism here only indicated schematically. According to the exemplaryarrangement of traversing mechanism as shown, which represents just oneof a large number of possible solutions within the scope of theinvention, the spindle rail 1 is connected at least at two points (oneonly being shown) to one of the vertical runs or legs of a chain 3revolving between an upper deflecting roll 4 and a lower deflecting roll5. One of the rolls 4 or 5 respectively, is driven alternatingly in bothdirections by a system known as such and not here described in greaterdetail, in such manner that the spindle rail 1 performs an alternatingup and down traversing movement as indicated by the double-headed arrowm.

The type of traversing mechanism chosen for effecting the verticalmovement of the spindle rail 1, required for distributing the rovingover the bobbin surface to form a package, is of no consequence asconcerns the specific teachings of the present invention, it is merelyof importance that the reversal of the vertical movement is effected bya device or means for scanning the spindle rail traverse stroke, as willbe explained later on in greater detail. Furthermore, the machine can beequipped with a traversing mechanism performing a constant stroke, sothat there are formed bobbin packages having cylindrical ends, or elsethe traversing mechanism can perform a stroke diminishing as a functionof the bobbin diameter, stroke diminishing as a function of the bobbindiameter, in order to produce bobbin packages having conical ends.

The solution for performing a diminishing traverse stroke here has beenchosen merely as an example, this solution corresponding to the usualarrangement in practical mill use. The solution described here, however,as will be explained clearly in the course of the description later on,advantageously also can be applied in a spinning preparatory machineperforming a constant traverse stroke.

On the spindle 2 a bobbin 6 is placed, onto which the fibre roving iswound to form a bobbin package. A flyer 7 is rotatably supported coaxialwith each spindle 2 in a flyer rail 8 arranged fixedly with respect tothe room. The spinning preparatory machine shown here thus is of thesuspended flyer type; this machine type, however, is exemplary and doesnot represent a condition absolutely required within the context of thepresent invention. The present invention also is applicable withoutdifficulties on any other known type of spinning preparatory machine(e.g. with "standing" flyer, with so-called "closed" flyers, i.e. flyersof the type guided only at their upper end, but not driven).

Above the flyers 7, which are arranged in correspondence to the spindles2 in one row or in a plurality of rows, there is furthermore provided adrafting arrangement consisting of cylinders 9 and 10 extending throughthe machine and coresponding pressure rolls 11 and 12. The fibre sliver14 coming from a can 13 is drafted in the drafting arrangement 9 through12 to a fineness desired and subsequently, while imparting twist, inknown manner, is transferred to the flyer 7 and finally to the bobbin 6of the spindle 2. In an arrangement of this type, control of the windingconditions on the bobbin 6, i.e. accurate control of the rotationalspeeds of the working elements, is of exceptional importance, as thewinding of the fibre roving 14 emerging from between the cylinders 9 and11 and not able to withstand any tensile tension, is to be effected freeof tension, or at a very low, controlled tension, respectively,throughout the whole bobbin package formation or build.

The present invention concerns an apparatus for controlling thesewinding conditions.

In the design example shown in FIG. 1 the drive of the working elementsis effected as follows:

An electrical motor 15 drives a main shaft 16 at constant speed. On thismain shaft 16 there is seated a bevel or conical gear 17, which mesheswith a bevel or conical gear 18 of a vertical shaft 19. On shaft 19there is rigidly mounted for rotation a belt pulley 20, for a belt 21cooperating with a belt pulley 22 provided on the flyer 7 in order torotate this flyer 7. The shaft 19 rotates with its axis being fixed inspace whereas the spindle rail 1 performs the up and down traversingmovement described above (according to the double-headed arrow m); forthis purpose the spindle rail 1 is provided with a large bore 23 forpiercingly receiving the shaft 19. In FIG. 1 the lowest position 1a ofthe spindle rail 1 has been indicated with broken or phantom lines. Theshaft 19 is provided at is upper end with a bevel gear 24 meshing with abevel gear 25 for driving the drafting arrangement 9 through 12 of thespinning preparatory machine. The cylinders or rolls 9 and 10 of thedrafting arrangement, extending throughout the machine, are supported inthe supports 26 and 27 which are rigidly connected with the flyer rail8; the support 27 furthermore is designed as a gear arrangement, i.e.also contains the gears (not shown) for transmitting the rotationalmovement of the gear 25 to both, or all, cylinders 9 and 10 of thedrafting arrangement, while taking into account the speed differencebetween the cylinders 9 and 10 required according to the draft(desired). The flyer 7 and the drafting arrangement times are thusdriven to be mutually synchronous at all times, since they arekinematically rigidly interconnected.

The rotational speed of the spindle 2 must be adapted according to theincreasing diameter of the bobbin 6, and this adaption must be effectedso accurately that the roving tension between the delivery cylinders orrolls 9, 11 and the flyer 7 is maintained as constant as possible.Experience has shown that this task cannot be merely achieved by using avariator controlled according to the known mathematical formula for theincrease in diameter. The external influence acting upon the fibreroving 14 during the winding operation (such as e.g. the air or climaticconditions) and the variations of the winding conditions alreadyinfluence the roving volume and the bobbin density in such a manner thata possibility of adaption, in the sense of a fine control active overthe whole bobbin build in addition to the variator mentioned, (even ifthe latter is working "theoretically correctly") is indispensable. Onlyif the roving tension, as mentioned above, is used directly as a controlvalue, a variator alone can fulfil the control function in principle,but this method shows the disadvantages cited initially and thus isunsatisfactory.

The present invention is based on the above mentioned findings, that(without direct measurement of the roving tension) a correct control ofthe rotational speed of the spindle only can be achieved by acombination of a basic control, which takes care of the average valuesof the technological characteristics (roving count, fibrecharacteristics, i.e. fineness, maturity, crimp, etc.) and a correctingcontrol which can be finely adapted or adjusted over the whole bobbinbuild or package formation.

This is achieved by using an apparatus according to FIG. 1 in such amanner that the main shaft 16 is used as input shaft of an infinitelyadjustable variator 28. The output shaft 29 of the variator 28 rotatesat a controlled rotational speed and drives, via the bevel gears 30/31,the vertical shaft 32, the belt pulley 33, the belt 34, the whorl 35,and thus the spindle 2.

The belt 21 as well as the belt 34 are preferably slippage-free toothedbelts, and in this case the pulleys 20, 22 and 33 as well as the whorl35 are provided with a suitable arrangement of teeth.

The rotational speed of the spindle 2 at each moment is adapted to theprevailing winding conditions by correspondingly adapting the infinitelyvariable variator 28, the variator 28 being adjusted or adapted by acontrol shaft 36 which is rotated stepwise, the control of whichrotatably indexible shaft concerns the actual subject matter of theinvention.

According to the invention the control shaft 36, which is rotatedstepwise, is driven by a setting or adjustment motor 39 which receivescontrol or switching impulses from a motor control device 37 via anelectric circuit or line 38. The stepwise rotation of the control shaft36 is activated by the deposition of the roving windings in layers onthe bobbin surface, which requires a stepwise adaptation of therotational speed of the spindle, according to the stepwise increase inbobbin diameter.

In FIG. 1 it will be seen that the control shaft 36 is provided with abelt pulley 40 for a toothed belt 41, by means of which there is driventhe belt pulley 42 of a device 47, comprising a worm gear 43, a gear 44and a cam or curve 45 provided with a gear rack 46 for determining thebobbin diameter.

The bobbin diameter-sensing or determining device 47 furthermorecomprises a contactor 48, which successively is brought into contactwith a plurality of contact transmitters 49 arranged along the path ofmovement of the contactor 48. Via the circuit or line 50 the contacttransmitters 49 are connected with the motor control 37, in such mannerthat the position of the contactor 48 relative to the plurality ofcontact transmitters 49 can be transmitted to the motor control device37.

The device 47, described here as an example, now functions as follows:If the bobbin 6 is empty, i.e. if an empty bobbin tube (not shown) isplaced onto the spindle 2, the variator 28 is set to its startingposition, as in this situation the spindle 2 is required to rotate atone of its extreme rotational speeds. In this starting position the camor curve 45, which kinematically is connected rigidly with the controlshaft 36 of the variator 28, also is arranged at its extreme right-handside position, in such manner that the contactor 48 is in contact withthe right-hand side contact transmitter 49; via the circuit or line 50 asignal is delivered to the motor control device 37, which signalcorresponds to this starting position, or to the smallest bobbindiameter, respectively.

As the diameter of the bobbin or bobbin package 6 increases, thevariator 28 must be adjusted correspondingly, which is effected bystepwise rotation or indexing of the control shaft 36: owing to therigid coupling between the control shaft 36 and the cam or curve 45, andthe contactor 48 respectively, each position of the control shaft 36,and of the variator 28 respectively, corresponds to a determinedposition of the cam or curve 45, since each position of the variator 28corresponds to a determined bobbin diameter. As a result, also eachposition of the cam or curve 45 thus corresponds to a determined bobbindiameter. The device 47 thus is able to deliver a signal via circuit 50to the motor control device 37, which corresponds to the momentarybobbin diameter, or to the momentary zone of the bobbin diametercorresponding to the spacing of the contact transmitters 49 along thepath of the contactor 48.

It is to be mentioned here already, that the device 47, described here,for controlling the bobbin diameter is not the only one which can beconsidered within the scope of the invention. In principle, any devicewhich can determine the diameter, or zones of diameters respectively, isapplicable within the scope of the invention. Thus, e.g. also directscanning of the bobbins, e.g. mechanically with direct contact of thebobbins, or e.g. contact-free optically, is applicable withoutdifficulties, as the only condition required consists in that a signalis to be given off via the electric circuit or line 50 to the motorcontrol device 37, which signal contains the information about themomentary diameter of the bobbin 6, subdivided, if required, into adetermined number of layers.

The depicted solution of the device 47 however, possesses as aparticular advantage, that it can achieve, in addition to thedetermination of the momentary bobbin diameter, also the control of thespindle rail traverse stroke during the bobbin formation or build, forachieving the desired contour or outline of the bobbin 6, in a manner tobe described hereinafter. For this purpose the cam or curve plate 45 isused, the curve edge or cam surface 51 of which corresponds to thedesired outline profile of the bobbin 6 in its cross-section (e.g. withtwo conical end portions). On the spindle rail 1 a limit switch 52 ismounted, which during the traversing movement of the spindle rail 1 isreversed at the upper and at the lower part of the curve or cam surface51. The reversing limit switch 52 thus transmits via the electriccircuit or line 53, at each reversal point of the spindle rail traversestroke, a signal to the motor control device 37, which signal isrequired for the inventive control to be described in detailhereinafter. At the same time, reversal of the switch 52 can effect, viatransmitting elements not shown, the reversal of the traversingmovement, i.e. reversal of the direction of movement of the chain 3,this, however, not being a condition required within the scope of theinvention.

Another design example of a device also suitable for determining thebobbin diameter is indicated in FIG. 1 with broken lines, which device,however, no longer is connected with the device for detecting thereversal points. There is shown schematically the manner in which theshaft of the pulley 42 (or the control shaft 36 directly, respectively)is coupled with a potentiometer 54; as the control shaft 36 rotates, thepotentiometer 54 also is rotated further, each of its positionscorresponding to a determined bobbin diameter. Via an electric circuitor line 55 the potentiometer 54, also in this arrangement, is connectedwith the motor control device 37 and transmits a signal to it, whichcorresponds to the momentary bobbin diameter.

The inventive layout of the motor control device 37 is shown in theblock diagram in FIG. 2, elements identical with the ones shown in FIG.1 being designated with the same reference numerals.

The motor control device 37 according to the invention comprises aprogrammable indicator or set value transmitter 56 for the desiredvalue, which from the outside can be set for a determined number ofswitching or indexing impulses per switching or indexing step. In itsbroadest layout according to FIG. 2, the indicator or set valuetransmitter 56 for the desired value is programmable according to adetermined relation between the spindle rotational speed V and thebobbin diameter D (V=f(D)) for the whole bobbin build or bobbin diameterrange. This relation, which e.g. can be the known mathematical relationgiven by the geometrical dimensions of the bobbin, is to be consideredas a first approximation of the control function, to which a correction,varying over the bobbin build as a function of the bobbin build ordiameter, is to be superimposed. This correction takes care of the outerinfluences mentioned initially, acting upon the bobbin build.

According to the invention it is of importance merely, that theindicator or set value transmitter 56 for the desired value can be setby the operating personnel from the outside. Setting can consist, e.g.in inputting to the indicator 56 for the desired value a determinedfunction V=F (D), which today can be achieved by various means (e.g. viaa programmable computer, or by scanning a control cam or curve, e.g.mechanically or optically, etc.).

If the indicator or set value transmitter 56 for the desired or setvalue functions by scanning a control cam or curve, the indicator 56 forthe desired value is to be arranged in such a manner that exchange ofthe control cam or curve or its adaption can be effected by theoperating personnel without tools, and without bringing the spinningpreparatory machine to a standstill. The indicator or set valuetransmitter 56 for the desired or set value is connected with thecircuit or line 50 via a branch circuit or line 57: via this circuit 57it receives signals from the device 47 for determining the bobbindiameter, which signals correspond to the bobbin diameter. The indicator56 for the desired or set value transmits via the electric circuit orline 50 a determined number of switching impulses to a logic device 59arranged subsequently. Furthermore, the motor control device 37according to the invention comprises a settable or adjustable correctionelement 60, by means of which the number of impulses determined by theindicator 56 of the desired value and corresponding to the relation V=f(D) is corrected by adding or subtracting correction impulses or pulsesduring each switching or indexing step. The correction element 60 alsois connected with the electric circuit or line 50 and is suppliedtherefrom with a signal corresponding to the bobbin diameter. Ittransmits its correction pulses or impulses to the logic device 59 viaan electric circuit or line 61. The control device according to FIG. 1now functions as follows:

Each time an adaption of the rotational speed of the spindles is to beeffected, since a new layer of roving is wound onto the bobbin 6 in sucha manner that the winding diameter of the bobbin 6 changes, the spindlerail 1 has reached one of the reversal points and thus activates thereversing switch 52. This switch in turn transmits (aside from thesignal for reversal of the traversing direction of the traversingmechanism, which is of no consequence in this context) a signal via thecircuit or line 53 to the motor control device 37, and to its logicdevice or element respectively. The logic device 59 obtains from the setvalue transmitter or indicator 56 for the desired or set value thenumber of control impulses corresponding to the bobbin diameter andadapted thereto, which indicate the approximating relation V=f (D). Fromthe correction element 60 the logic device 59 simultaneously obtains thecorrection corresponding to, and adapted to, the bobbin diameter, whichcorrection consists in a determined number of negative or positivepulses. The logic device 59 sums up the pulses from the indicator 56 forthe desired or set value and from the correction element 60, andtransmits via the circuit or line 38 a control or adjustment signalcorresponding to the momentary winding conditions to the control oradjustment motor 39. The adjustment of the control or adjustment motor39 is checked by using a feedback arrangement (comprising a signaltransmitter 62 and an electrical circuit 63, both indicated with brokenlines), which establishes the connection between the control motor 39and the control device 37.

The control arrangement, described here, for a spinning preparatorymachine presents the great advantage that, owing to the separate roughcontrol using the set value transmitter or indicator 56 for the desiredvalue, and the separate time control using the correction element 60 acomfortable and extremely accurate control of the spindle speed over thewhole bobbin build or package formation can be effected. Furthermore, itpermits the application of any type of variator 28, since it does notrequire a given transmission ratio characteristic for the variator 28.This results from the programmability of the indicator 56 for thedesired or set value, which without difficulties can be chosen such thatit can take care of any desired transmission ratio characteristic of thevariator 28.

Further advantages are presented by a preferred embodiment of theinvention if the indicator or set value transmitter 56 for the desiredvalue as well as the correction element 60 are freely accessible to theoperating personnel, i.e. without opening of housing covers, e.g. at thedrive head stock of the machine, and can be set or adapted while themachine is running. Thus, the operating personnel can effect theadaption of the spindle rotational speed as required, without disturbingthe tension conditions prevailing in the roving 14, which are to becorrected by stopping the machine. It is known that any stopping orstart-up operation always influences the roving tension, or the windingtension, respectively, as it depends to a great extent on thecentrifugal force and on the air drag. If now the operating personnele.g. detects too slack a roving tension in a given phase of the windingprocess, they can effect a corresponding correction at the correctionelement 60 while the machine is running and immediately can check thesuccess of the corrective action. If, on the other hand, as withconventional machines, the machine is to be stopped first, and thecorrection is to be effected while the machine is at a standstill, andthe machine thereupon is to be restarted again, the danger persists,that the influence of the stopping of the machine and of its restartingexceeds the correction to be effected, in which manner the correctionoperation is rendered difficult, if not impossible, as it is to beeffected step by step in a long series of operations.

A very interesting simplification of the inventive control arrangementcan be achieved using a further preferred embodiment of the invention,which provides that the employed variator 28, over its whole controlrange shows a transmission ratio characteristic, which, using a linearcontrol movement or adjustment, achieves a first approximation of therelation, known as such, between the spindle rotational speed and thebobbin diameter. The variator 28, in other words, can be designed such,that, if the control shaft 36 is further rotated always through the sameamount, i.e. is moved or adjusted linearly, the ratio of the rotationalspeed of the main shaft 16 to that of the output shaft 29 in a firstapproximation equals the known, non-linear relation between the spindlerotational speed and the bobbin diameter. In this case it is sufficient,to set the set value transmitter or indicator 56 for the desired or setvalue to a number of switching pulses or impulses, which remainsconstant over the whole bobbin build, which represents a veryconsiderable simplification, concerning the indicator 56 for the desiredvalue, which in this case can be in the form of a decade switch 64, asshown in FIG. 3, as well as concerning the operation of the machinesince only this constant value, but not its progress over the wholebobbin build, is to be set or adjusted.

Also advantageous is an inventive control apparatus, in which thecontrol or adjustment motor 39 is chosen as a so-called stepping motor,i.e. a motor, which rotates stepwise over an angle or amountrespectively, corresponding to the control pulses or impulsestransmitted to it. If a motor of this type is employed, then the use ofa feedback arrangement comprising a signal transmitter 62 and anelectrical circuit 63 (FIG. 2) can be dispensed with, since the motoralways is rotated through the correct angle. In FIG. 3, a particularlyadvantageous design example according to the invention is shown, inwhich the correction element consists of a crossbar distributor 65, oneof the coordinates of which e.g. as shown in FIG. 3, the abscissa a,represents the bobbin diameter D, and the other, the ordinate b,represents the positive or negative correction of the number of impulsesor pulses. As shown in FIG. 3, the contacting points of the contacttransmitters 49, which are designed exactly like the ones shown in FIG.1, are connected with the vertical bars of the crossbar distributorarrangement 65. Each vertical bar or rail thus corresponds to an exactlydetermined range of diameters, or to a layer, respectively, of thebobbin 6. In FIG. 3, e.g. six bars or rails are provided, i.e. thebobbin is subdivided into six cylindrical layers. The horizontal bars orrails of the crossbar distributor arrangement 65 are connectedindividually with the logic device or element 59. In this arrangement,the pulse scale b is subdivided into positive and negative values;points above the zero line correspond to increasing positive corrections(e.g. to positive pulse numbers, which, if summed up in the logic deviceor element 59 with the ones from the decade switch 64, effect anincrease in the spindle rotational speed over the one corresponding tothe set or adjusted desired or set value), whereas below the zero linethe negative correction can be set. Setting of the correction in acrossbar distributor arrangement 65 is effected in known manner byestablishing the contact between the vertical and the horizontal bars orrails, using e.g. contacting pins 66. In the example shown in FIG. 3,e.g. in the first layer of the bobbin 6 a positive correction of +2impulses is set, in the second layer one of zero impulses, and in thethird layer one of +1 impulse.

The use of a crossbar distributor arrangement 65 as a correctionelement, which of course also can be equipped with considerably morebars or rails, is very comfortable and easily recognizable for theoperating personnel, and is suitable for the use of pin setting cards(cards on which the corrections used in a specific application are notedby punching the crossing points) for storing the correction adopted in aspecific case for later re-use.

The electrical connections required for realisation of the inventiveblock diagrams described herein are known to any specialist skilled inthe art and a more detailed description thereof thus can be dispensedwith.

While there are shown and described present preferred embodiments of theinvention, it is to be distinctly understood that the invention is notlimited thereto, but may be otherwise variously embodied and practicedwithin the scope of the following claims. Accordingly,

We claim:
 1. An apparatus for controlling the rotational speed ofspindles of a spinning preparatory machine as a function of theincreasing bobbin diameter of bobbins carried by the spindles and uponeach of which bobbins there is formed a bobbin package, wherein flyersare operatively associated with the spindles carried by a spindle railperforming traversing movements, comprising:an infinitely adjustablevariator for the drive of the spindles; a stepwise indexible controlshaft for infinitely adjusting said variator; an electric adjustmentmotor for driving said control shaft; motor control means for inputtingcontrol pulses to said electric adjustment motor; said motor controlmeans comprising a programmable set value transmitter which can beexternally set to a predetermined number of control switching pulses foreach indexing step of said control shaft; said motor control meansfurther comprising an externally settable correction element forcorrecting the number of pulses determined by the set value transmitterby the addition or subtraction of correction pulses during each indexingstep; scanning means for scanning reversal points of a traversing strokeof the spindle rail carrying the spindles; said scanning meansdelivering a command for outputting the control switching pulses of themotor control means; means for determining the increasing bobbindiameter; and at least any one of said set value transmitter and saidcorrection element being operatively connected with said means fordetermining the increasing bobbin diameter.
 2. The apparatus as definedin claim 1, wherein:said set value transmitter and said correctionelement are freely accessible to the operating personnel and can be setduring operation of the spinning preparatory machine.
 3. The apparatusas defined in claim 1, wherin:said variator has a regulation rangethroughout which there prevails a transmission ratio which, with alinear setting thereof, realises a first approximation of theinterrelationship between the spindle rotational speed and the bobbindiameter; and said set value transmitter is set throughout the entirebobbin package formation to a constant number of control switchingpulses per indexing step.
 4. The apparatus as defined in claim 1,wherein:said adjustment motor comprises a stepping motor.
 5. Theapparatus as defined in claim 1, wherein:said correction elementcomprises a crossbar distributor defining two coordinates, wherein oneof the coordinates signifies the bobbin diameter and the othercoordinate signifies a positive or negative pulse number correction. 6.The apparatus as defined in claim 1, further including:means forkinematically rigidly coupling said means for determining the bobbindiameter with the control shaft of said variator.